Membership: paypal link issue

When testing in paypal sandbox to get membership to work with a subscription, I get to PayPal in the checkout process then hit the Pay button and get “The link you have used to enter the PayPal system is invalid. Please review the link and try again.”

In past posts, this has been solved by making sure that the account was verified. My account is verified, but I’m still getting the error. What should I do now?